Why does the professor discuss the presence of zinc in paint pigments？A．To explain why som

Why does the professor discuss the presence of zinc in paint pigments？

A．To explain why some paints may deteriorate over the course of time

B．To stress the need for caution when attempting to restore old artworks

C．To show how pigments differ from varnishes and binding agents

D．To show how spectroscopy can help establish the age of a painting

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